I own a lawn service so have had to deal with manual labor a lot and I'll tell you that honestly, it's not about what the job pays, it's that "white" guys really don't want to work hard, or do manual labor at all. I've paid leads $800 - $900 per week and helpers $500 - $700 per week, to cut grass, and still can't get "white" guys to do the job. The few that would take the job had problems that manifested as soon as they got a paycheck or two and remembered how much they liked drugs/alcohol now that they could afford it again. The labor problem for construction, landscaping, restaurants, etc. is bad. In fact, it got to be such a hassle that we've subbed all of our work out so that we don't have to directly deal with it anymore. We still have to some but now we have a lot more labor available to us than we need so we're able to spread things out on the others when we have problems with one (or more) of the subs.
It's such a political issue though, it probably won't get solved anytime soon. W came the closest to what I believe is reasonable, this country needs a workable guest worker program but there's no political will to do so. I think it's because many, probably most, illegals work on false documents so teh government is unwilling to give up that "free" money from them paying into the system but not ever filing returns.